The use of light to promote chemical reactions has long been known and, in the art of photochemistry, it is known to utilize actinic radiation, for example, to promote polymerization reactions. It is also known to utilize selected frequencies of light to induce chemical decompositions or chemical exchange, substitution or replacement reactions.
For the present application, terms such as "promotion," "catalytic activation" and "enhancement" insofar as they are intended to connote the activation of a chemical species so as to induce, maintain or facilitate chemical reaction are intended to be equivalent and to signify that the reaction may be in part or entirely initiated by the photons of light energy which are supplied, that the photons maintain the reaction after it has been initiated by light catalysis or otherwise, or that the photons provide some other effect which allows a chemical reaction to proceed.
In the past, it has been recognized that many chemical reactions involve the specific "opening" of a given chemical bond in one or more molecules to allow the recombination of such molecules into new compounds. Often such reactions are facilitated by carrying out the reactions on catalytic substrates, typically transition metals or their oxides, and particularly metals of the platinum group. The intermediating action of these substrates is believed to provide the activation of target electron orbitals to allow the reactions, without the substrate actually participating in the reaction. Such catalytic reactions are often subject to poisoning by impurities in that the active sites on the substrate become permanently bonded to, or otherwise affected by the "poisoning" species. Optically enhanced chemical reactions can be considered to be reactions catalyzed via the intermediate activation of orbital electrons or the outright ionization of molecular species. While optical radiation for enhancing chemical reaction rates is not widespread in industry, one could classify many polymerization processes as optically enhanced catalytic processes. The use of light in the enhancement of chemical reactions is therefore well known.
One of the problems encountered in the application of light to the enhancement of chemical reactions is due to the fact that if the light source contains wavelengths that are indeed beneficial to a given reaction, it is because the light at these wavelengths is absorbed by the reactants by the interaction with orbital electrons, or by the ionization of the molecules, or by selective breaking of chemical bonds between radicals attached to various host compounds or polymer backbones. This limits the use of such optical activation type processes to relatively thin films, and it has not been possible, to date, to carry out such optically activated chemical reactions or optically enhance catalytic reactions in the bulk.